Light Trucks No Lightweights

TO state the obvious, light trucks and SUVs are heavier than passenger cars, and heavier weights require more stopping power. So there should be little surprise that these vehicle designs put more stress on their respective brake components.

Operating temperatures alone can exceed 750 degrees F when stopping a pick-up truck, suggests Quing Zheng of Newtek Automotive. “Sometimes the steel becomes blue, even red, and the friction coefficient drops dramatically.”

Even though these brake systems are proportionally larger than their counterparts found on passenger cars, there is still an ever-present push to design smaller packages that will help reduce vehicle weights, says Affinia’s Brian Fleming.

But here’s the biggest challenge of all: the owners of late-model versions of these vehicles are looking for something closer to a passenger car’s performance. They may have been willing to sacrifice noise and premature wear when pick-ups were simply mechanized mules for job sites, but minimizing noise, vibration and harshness (NVH) is more important when commuting to the office or grocery store.

“They’re not just utility vehicles. They’re statements. They’re designer trucks,” says Ian Braunstein, vice-president of sales and marketing at Satisfied Brake Products. “How many Escalades are running with a payload of brick?”

That may require jobbers to reconsider the products they promote.

“We have to redefine what aggressive means,” Braunstein says, referring to the feature often sought in the friction material for pick-ups and SUVs. “Today, you have to make sure your aggressive pad is not causing premature rotor wear, noise or brake dust.”

The demands simply reflect a change in buyers.

“Light truck and SUV owners are clearly more sophisticated in terms of their expectations of product value and performance than they were 10 years ago,” says Akebono’s Ken Selinger.

Still, the control of NVH is easier said than done, particularly when bigger vehicles are involved. An attribute such as stopping power can sometimes come at the expense of another feature such as a quieter sound, Fleming says. “The trick is to come up with the right formula that’s going to bring you to the edge.”

For some manufacturers, a solution is seen in ceramic offerings, rather than the semi-met designs that have tended to rule the world of trucks.

“Five years ago, ceramic pads accounted for 9% of all disc pads sold in North America. Today, they account for over 38%. That’s a huge increase,” Selinger says. And the shift hasn’t ended yet. Between 2000 and 2004, virtually every GM light truck and SUV incorporated Akebono’s ceramic friction material, he adds, crediting part of that growth to the improving friction coefficients of the material.

“The obvious benefit to the ceramic category is its ability to control noise, vibration and harshness,” Selinger says, noting that those issues continue to be the leading factor in most related service comebacks.

The choice of friction material, however, is still a matter of opinion. Jack McGrail of Robert Bosch, for example, suggests that semi-metallic pads are still able to handle the related heat more effectively.

“One ceramic does not necessarily fit all, just as one semi-metallic does not fit all,” Braunstein suggests. “There are very specific vehicle needs, with very specific demands. We are very application-specific in how we make materials today.”

The owners of light trucks and SUVs do seem willing to embrace premium brake products to meet their needs, however. While about 75% of passenger car owners buy such products, as many as 85% of light truck owners will treat their vehicles to a better choice, Fleming says.

There could also be some regional factors behind the higher percentage, though. Western Canadians are more likely to buy pick-ups and SUVs than their counterparts to the east, while the suppliers of economy brake designs tend to target major urban centres like Toronto, Montreal and Vancouver, he says. Value-priced designs may simply be less of a competitive threat in Prairie markets.

Regardless of the reason they’re purchased, the differences between premium and value-priced components can be dramatic.

Premium friction materials, for example, will see their friction values deviate by less than 10% over a wide range of operating temperatures, Selinger says. But in a cheaper line, the coefficient of friction can drop to as low as 0.10 at higher temperatures, compared to the 0.35 enjoyed at ambient temperatures. (A 0.18 coefficient of friction is more common in the lower-priced products.)

What does that lower number really mean?

“You could equate that to trying to stop a vehicle on a sheet of ice,” he says.

But selecting one product over another can be challenging because of a lack of mandated testing standards in the aftermarket. Europe requires friction material to be validated by an R90 stamp of approval; North America has no equivalent.

“You could put cardboard in the box and call it a brake pad,” says Jack Fisher, Canadian territory sales manager for Perfor-mance Friction.

McGrail sees it as an important reason to stick with trusted brands.

“It makes it imperative that you are comfortable with, and have confidence in, your supplier,” he says.

Even if they want to favour some sort of additional testing, however, jobbers need to decide whether to embrace Dual Dynamometer Differential Effectiveness Analysis (D3EA) standards, or the Brake Effectiveness Evaluation Procedure (BEEP) from the Brake Manufacturers Council. A BEEP test uses a single-ended dynamometer to validate brake performance on the front or rear axle, while D3EA tests are conducted on a dual-ended dynamometer that simultaneously tests front and rear replacement linings. The Brake Council suggests its standard better reflects the fact that brake jobs seldom involve both axles. Greening Testing Laboratories, which performs the D3EA testing, contends that its test can be correlated to full vehicle tests that automakers are required to conform to.

Those who follow the standards suggest that additional testing should be seen as an important factor when selecting one product line over another.

“Testing costs us a lot of money,” Braunstein says, “but there’s a sense of responsibility that should come in an unregulated environment, and for this reason we invest greatly in D3EA and other related testing.”

Fisher, meanwhile, says it’s important to look to manufacturers that do on-vehicle testing rather than simply relying on lab results. Performance Friction has a fleet of 20 vehicles used specifically for the purpose.

That’s not to suggest that any pick-up with value-priced brakes is going to slam into every car it follows.

“They’re not great performers over the long term, but they all stop the vehicle to some degree,” Selinger says, suggesting that the industry doesn’t require mandated tests. “Right now, it’s better that we regulate ourselves.”

Even when premium friction material is selected for one of these heavier vehicles, their demanding braking needs make it more important than ever to promote full brake jobs to limit callbacks, Braunstein says, referring to such components as shims, hardware and even brake rotors that can contribute to issues such as excessive noise. “Everything plays a role.”

A quality rotor is also important, McGrail says, adding that high heat associated with these vehicles can lead to warping.

Like the friction material, however, hardware has evolved to meet demands. In the past five or six years, there has been a shift from single-piston to dual-piston calipers on front brakes, while rotor sizes have increased, says Canamotive’s Paul Meleca.

And while cheap rotors are on the market, they tend to be smaller, lighter and thinner than their counterparts, Meleca warns.

For jobbers, that means asking some important questions when a shop calls for friction material.

“They need to ensure that they’re selling the complete brake job. Make sure all the parts are checked, and that [the shop is] replacing everything that needs to be replaced,” Fleming says. If selling parts for the larger vehicles, it may be time to recommend a severe-duty product.

By asking shops whether they have the lubricant for the caliper pins, a jobber can subtly suggest the need for a full brake job, adds McGrail. “It allows them to have additional sales, but at the same time it’s a good reminder to really do a full and complete job.”